Modified Preauricular Transparotid Approach for Treating Mandibular Condylar Fractures

Aim of the Study: We introduce a technical variant of the standard preauricular approach to treat intracapsular and condylar neck fractures: the modified preauricular transparotid approach (MPTA). The main modification, when compared with the conventional submandibular approach, is that the incision of the superficial musculoaponeurotic system is performed directly above the parotid gland, and the buccal branch of the facial nerve is dissected in a retrograde way within the parotid gland. Case Series: Between January 2019 and December 2020 at the Maxillofacial Departments of “Ospedale Maggiore” of Parma and “Policlinico San Martino” of Genoa 6 patients affected by intracapsular and condylar neck fractures underwent open reduction and internal with MPTA. Surgery was uneventful in all patients; no infections occurred in any of the cases; the mean procedure duration was 85 minutes, ranging from 75 to 115 minutes. At the 1-year follow-up, all patients had stable occlusion with a natural, well-balanced morphology of the face and adequate dynamic excursion of the mandible. Conclusion: MPTA is particularly suited for intracapsular and condylar neck fractures. Morbidity is negligible in terms of damage to the facial nerve, vascular injuries, and esthetic deformity.

C ondylar process fracture is one of the most common man- dibular fractures, with an incidence ranging from 29 to 52%. 1,2ondyle fracture can be classified into intracapsular, neck fracture, and subcondylar fracture according to the location of the lesion; intracapsular condylar fracture is the most common, accounting for 65% of all cases. 3There are several reported transfacial approaches and technical variants to gain direct access to the mandibular condyle.][6] The submandibular and retromandibular approaches are widely described for condylar base fractures.However, these approaches are not well suited for intracapsular or condylar neck fractures because the surgical incisions are below the level of the Loukota line. 7Intra-oral access using an endoscopicassisted method, which reduces the risk of facial nerve injury and external scars, is an alternative approach.However, this procedure requires expensive equipment and a long-term learning curve, especially in the treatment of condylar neck fractures; moreover, it does not allow for easy treatment of medially displaced condylar fractures. 8 preauricular incision is usually used to approach condylar fractures within the TMJ capsule or condylar neck fracture.This approach was initially described by Rowe & Killey. 9This technique has been advocated for its advantages, such as direct access to the joint and easy manipulation of the fracture segments with a hidden scar.However, extreme downward stretching is usually required to expose enough intact condylar bone for rigid fixation, and the view of the surgical field is not directly perpendicular but oblique; moreover, the zygomatic branch of the facial nerve is at risk of injury during surgery due to tissue stretching; the incidence of facial nerve paresis ranges from 1% to 32% following this approach. 10We introduce a technical variant of the standard preauricular approach to treat intracapsular and condylar neck fractures: the modified preauricular transparotid approach (MPTA).The main modification, when compared with the conventional submandibular approach, is that the incision of the superficial musculoaponeurotic system is performed directly above the parotid gland, and the buccal branch of the facial nerve is dissected in a retrograde way within the parotid gland.

MATERIALS AND METHODS
A retrospective chart review was conducted for all patients affected by intracapsular and condylar neck fractures who underwent open reduction and internal fixation (ORIF) through the MPTA between January 2019 and December 2020 at the Maxillofacial Departments of the University Hospital of Parma and "Policlinico San Martino" of Genoa.This study was conducted in accordance with the current version of the Declaration of Helsinki.Written informed consent was obtained from all patients for publishing data and images.The current standards of scientific research ethics were applied while performing this retrospective study.Our study was exempted by our local ethics committee.
The diagnosis was performed by clinical examination and computed tomography (CT); all patients consented to have condylar fractures treated with miniplates and screws osteosynthesis through MPTA.
Patient inclusion criteria were as follows: patients with an intracapsular or condylar neck fracture; surgeries performed using the MPTA approach; cases with available preoperative clinical data; and patients with a postoperative follow-up of at least 1 year.
The exclusion criteria were as follows: treatment with surgical techniques other than ORIF by MPTA and patients with insufficient preoperative and postoperative clinical data.Follow-up was performed at 1 week, 1 month, 3 months, 6 months, and 1 year postoperatively.During the postoperative follow-up examinations, all patients underwent CT scan.

SURGICAL TECHNIQUE Preparation
With the patient supine, under general anesthesia with nasotracheal intubation, and with the head in a neutral position, we mark the mandible, the zygoma, and the glenoid fossa as pertinent landmarks of the face.We prepare and drape the entire face; we shave the preauricular hair and place a cotton bud soaked into antibiotic ointment in the external auditory canal.The preauricular incision is slowly infiltrated with 5 to 10 mL of physiological solution and adrenaline in a strict subcutaneous plane to facilitate surgical dissection and hemostasis.

Incision of Skin and Parotid Fascia
We make a vertical incision 4 to 5 cm long in the preauricular region through skin and subcutaneous tissue.The edges of the incision are from the tragus and 0.5 to 1 cm below the insertion of the lobule.Surgical dissection proceeds with the incision of the parotid fascia and exposure of the anterior margin of the gland.

Retrograde Dissection of the Facial Nerve
Once the anterior margin of the parotid gland is identified, the zygomatic branch of the facial nerve is identified 1 cm below the zygomatic arch and with retrograde dissection exposed until the posterior margin of the masseter muscle is reached.Under direct vision of the nerve, the masseter muscle is incised with electrocautery (Fig. 1).

The Mandibular Skeleton
We manipulated the mandible open and closed to find out the location of the condylar fracture.When the bony surface is reached, wide subperiosteal dissection of the mandibular skeleton is completed to expose the fracture.After anatomic reduction, osteosynthesis is performed under temporary intermaxillary fixation using titanium miniplates.

Closure
After checking the occlusion, the surgical site is generously irrigated with hydrogen peroxide, and any hemorrhage is meticulously controlled.We close the parotid capsule tightly with an absorbable, running, horizontal mattress suture.The skin is closed with interrupted sutures using nonresorbing suture material (Fig. 2).

RESULTS
Eight patients with condylar fractures underwent ORIF through MPTA during the study period.Two patients were excluded because of inadequate records.The final study sample included 6 patients (5 females and 1 male).The mean age of the patients was 29.6 years (range, 17-52 y) at the time of surgery.The main cause of injury was traffic accidents (4 cases [67%]), followed by fights (1 [17%]) and sports injury (1 [ 17%]).The average time between the trauma and surgery was 2.9 days.
Four patients presented with unilateral fractures and two patients presented with bilateral fractures.Two patients presented with associated fractures of the facial bones (1 patient with mandibular body fracture, and 1 with maxillary fracture).Two patients presented intracapsular condylar fracture; 4 patients reported condylar neck fracture.The mean preoperative oral opening was 28 mm (range, 22-38 mm).Surgery was uneventful in all patients; the mean procedure duration was 99 min (range, 76-115 min).A postoperative CT scan was taken to check for fracture osteosynthesis (Fig. 3).Clinical follow-up was performed at 1 week, 1 month, 3 months, and 6 months.All patients underwent physiotherapy after surgery for recovery of mandibular movements.The mean postoperative oral opening was 39 mm (range, 34-48 mm).The mean follow-up period was 1.1 years (range, 1-1.4 y).Postoperatively, there was no infection or hematoma.Temporary weakness of the mandibular branch of the facial nerve was observed in 1 case, with recovery to normal function after 6 months; no patients had permanent facial nerve weakness.
At the 1-year follow-up, all patients had stable occlusion with a natural, well-balanced morphology of the face, and adequate dynamic excursion of the mandible.All patients showed complete ossification of the previous fracture and alignment of the condyle.

DISCUSSION
The 3 main transfacial approaches to the condylar region are the preauricular, retromandibular, and submandibular approaches.Each of these incisions has its own advantages and disadvantages.The preauricular approach is mainly indicated for the reduction of middle or high mandibular condyle frac-However, sufficient surgical exposure is difficult with this approach due to the effect of the zygomatic branch of the facial nerve, which limits the range of downward traction.Due to this fact, the view of the surgical field is not directly perpendicular but oblique; therefore, it can be troublesome to adequately skeletonize the distal stump of the fracture and reach the medially displaced condylar head.2][13] The facelift approach is a technical variant that provides more exposure than the preauricular approach combined with a cosmetically acceptable site for the skin incision.It is useful for procedures involving the area on or near the condylar neck/head. 14The retroauricular transmeatal approach can be considered a technical variant of the preauricular approach, and this method is advocated for higher fractures of the condylar head; however, it can be a challenging approach for fractures of the condylar base. 15The retromandibular approach permits exposure of the ramus, condyle, and coronoid processes.This approach can be retroparotid, transparotid, or preparotid.The 3 main concerns about this approach are the potential injury to the facial nerve, postoperative salivary complications related to damage to the parotid, and visibility of the scar. 16In this approach as well the view of the surgical field is not directly perpendicular but oblique; therefore, it can be troublesome to adequately skeletonize the condylar stump.The submandibular approach, also called the Risdon approach, is mainly used for middle or low mandibular condyle.The incision is relatively long (1.5-2.0 cm) and is distant from the fracture site, but scarring is not an issue, and facial nerve injury is rare.However, traction of the periosteum and soft tissue limits access to the surgical field, and distance increases the surgical difficulty and risk of surgical trauma.Classic variants of this approach include a posterior extension towards the mastoid region and an anterior extension towards the submental region, with or without a 'stepped/zigzag' incision or a lip-splitting approach. 17ecause of these issues, it is rarely used for condylar fracture.
The retromandibular approach provides a more direct visual field and nearly straight-line access for fracture fixation.9][20][21][22][23] Al-Moraissi et al, 24 in a meta-analysis performed on 96 studies, reported that the retromandibular approach was responsible for 6.8% of the permanent facial palsy rate.In the same study, the preauricular approach was responsible for 5% of permanent facial nerve damage.According to Weinberg, 25 the branch of the facial nerve that is most vulnerable to injury during dissection in the TMJ area is the temporal branch because it lies more superficially than the other branches between the superficial layer of the deep temporal fascia and the superficial temporal fascia.The nerve, however, is occasionally found deep within the superficial fat pad.This anatomic variation may result in injury to the facial nerve during a standard preauricular approach.
With these problems in mind, we have introduced a safer surgical approach: the MPTA.
In contrast to the conventional technique used in the traditional preauricular approach, the edges of the incision are from the tragus and 0.5-1 cm below the insertion of the lobule; the superficial musculoaponeurotic system is exposed, and it is cut obliquely towards the ear lobe, thereby exposing the underlying parotid gland.The zygomatic branch of the facial nerve is identified at the anterior border of the parotid gland and below the zygomatic arch; it is dissected in a retrograde way to protect and retract it within the substance of the posteriorly retracted flap.
Using this modified surgical technique, we can maximally prevent facial nerve injury because it is constantly under direct control.Moreover, damage of the middle branch of the facial nerve is better tolerated than damage of the frontal branch of the facial nerve.
Advantages of MPTA are as follows: (1) Shorter incision in the preauricular area when compared to the standard preauricular area (less swelling and postoperative scarring, faster healing; (2) The surgical incision is close to the fracture site.Hence, the bone surface is exposed without excessive soft tissue distraction; (3) The incision ensures the direct vision of the surgical site; thus, the surgeon's visual angle is vertical to the lateral side of the condyle.Titanium screws can be placed perpendicular to the fracture; (4) Using a small incision of the parotid gland the facial nerve is visible and it is dissected in a retrograde way to protect it.Drawbacks of this procedure are the technical difficulty of isolating the zygomatic branch of the facial nerve that requires experience in parotid surgery/facial nerve surgery and the constant attention required during osteosynthesis not to damage the branches of the facial nerve, which must be constantly protected by retractors.Regarding complications, we did not observe any permanent facial nerve damage, salivary fistula, or Frey's syndrome using this approach.Even if hematomas or wound infections are possible, as in other trans facial approaches, we did not report these complications during the postoperative follow-up.The surgical scar within the preauricular area is highly acceptable.The limitation of our report is that it is a non-randomized study with a relatively small sample without a control group.

CONCLUSION
Although we cannot draw any significant conclusions, in our opinion, the MPTA is particularly suited for comminuted and medially displaced condylar fractures.Morbidity is negligible in terms of damage to the facial nerve, vascular injuries, and esthetic deformity.We believe that further prospective clinical trials are necessary to assess and develop this approach.